Automatic slack adjuster for air brakes



Feb. 28, 1928. 1,661,032

w. s. DE CAMP AUTOMATIC SLACK ADJUSTER FOR AIR BRAKES Filed June 29, 1926 2 Sheets-Sheet -l Feb. 28, 1928. 1,661,032

w. s, DE cAMP v AUTOMATIC 'SLACK ADJUSTER FOR AIR BRAKES Filed June 29. 1926 2 Sheets-Sheet 2 ATTORNEYS Patented Feb. 28, 1928.

'UNITED' STATES WILLIAM s.` mi CAMP,

PATENT OFFICE.

or cHILLIco'rHE, oHIo.

AUTOMATIC sLAcK ADJUSTER Fon AIR BRAKES.

Application sie@ June 2 9, 1926. serial No. 119,407.

a device for automatically making adjust ments in the `brake connection When needed in order to take up any Vslackin the brake shoes brought about by thewear thereon incidental to repeated application, one of the outstanding features being the provision for a full application stroke-of the piston as distinguished from but partial application strokes in other constructions, and the fperformance of the adjustment for eliminating the foregoing slack on therelease stroke of the piston. `v

Other objects and advantages appear in the following specification, reference being had to the accompanying drawings, in which i j Figure l is a-diagrammatic` perspective View of enough of an air brake system for reference in connection with the slack adjuster.

Figure 2 is'a longitudinal section ofthe brake cylinder taken substantially on the line 2-2 of Figure l, the piston being shown in the brake-shoe releasing position. Y

Figure 3 is a longitudinal section taken on the line 3--3 of Figure 2.

Figure 4 is a detail elevation of the'pawl and bracket hereinafter referred to.

Figure 5 is a sectional diagram "showing the position ofthe piston at the end of the full application stroke, the positions-of the associated parts indicating that` the brake shoes are comparatively new. V

Figure 6 is a similar diagram, the position of parts indicating that thebrake shoes have begun towear, the piston being in the release position. i

`Figure 7 is adetail perspective view of the automatically extensible core.

Figure 8 is a detail perspective view of the improved bushing against Which one end of the spring rests. I c

Figure 9 is a cross section taken on the line 9-9 of Figure 3. j

Figure 10 is a. section taken substantially -on the line 10-10 of Figure 5, the View bei ing of diagrammatic order to illustrate the' action of the pawls as later described.

Figure 11 is a sectional view of the brake cylinder Ias applied in the vertical position for usefon locomotives.

Figure l2 is `a detail perspective View of the washer and key hereinafter referred to. This invention is an improvement on the slack adjuster for air brakes disclosed in my co-pending `application tiled October 30,V

1925, Serial #65,817, `reference also` being had to my Pate-nt 1,560,980 ofNovember 10, 1925, for automatic slack adjusters.

As brought out in the foregoing application and patent the purpose of the slack adjuster, as the name implies, is to make such adjustments 1n the connections of the brake` system from time to time aswill keep the `brake shoes in such positions relative to the treads ofthe shoes asv will permit aproper application of the shoes for the brakingaction. Such adjustments are made from time to time as needed, and the-action is `automatic. In each of the foregoing casesthe adjustment for taking up slackoccurred `on the application stroke of the piston, in other `certain times, this beingof particular ad` vantage in casethe brake `shoes should break or come otl'.-

Some-ofthe elements of the presentconstruction are disclosed in each of the fore going cases, and prior to'disclosing ythe pres ent invention `these. elements are` described in order that a general understanding may be had. l designates a brake cylinderwhich has heads `3 and l` respectively known asthe non-pressure andpressure heads by virtue of `the fact that the latter subjected to internal air pressure and the former is not. AThe first i head includes atubularextension 5,and also an annular shoulder' 2 upon lwhich the cylinder l lits, the shoulder serving to centralize one y part in respect to the other. The head 4 has ing rocking ofthe cylinder' lever 8 (Fig. l)

so that power is applied to the pull rods E) and in the direction of the arrows for the purpose of applying the brakes. The eirtremities ,of Vthe pull rods have connection with brake levers 11 and 12 which in vturn act upon the brake shoes 13 and 14, moving vthem against the treads or bases of the wheels 15 in order to perform the braking action as stated.

The foregoing` structure is to be found on passenger, freight and street cars as well as on locomotives, but for the latter purpose thek cylinder is held erect as in Figure 11 rather than horizontal for the other pur poses.

A piston 21 situated in the cylinder 1 moves to the left when compressed air is i admitted to perform whatis known as the application stroke. The piston is secured 'to the plunger by suitable means, the pin being preferable because it must also pass through the sleeve 32 and inner section 36 of the plunger so that all these things are `securedtogether and may move as one. The

.which the threaded stein is formed.

I section 36 has ay threaded bore 39. The pisa ton includes a short threaded stem 22 upon which the portion y23 is screwed until it engages the shoulder of the portion. 24Ton he usual cup leather and washer Vof the piston are held in place by a nut 27.

A bushing 16 guides the plunger 7. This bushing has a circular flange 17 abutting the circular shoulder 18 formed within the ertremity of the tubular extension 5. The bushing is held in place by one or more pins 18 (Fig. 2).

A spring 43 rests against the circular flange 17 at one end, and at the other end rests against a washer 44 which is loosely litted upon the sleeve 32 of the plunger 7. The purpose of the spring is to return the piston after an application stroke, it being upon the release stroke thus performed by the spring that the adjustments for taking up slack are made. The washer 44 has a long narrow extension or key 51 which lits in the groove 52 in the bushing 16 (Figs. 2 and u 8). Inasmuch as the bushing 16 is liXed,

rotation of neither the washer 44 nor the spring 43 can take place upon the foregoing release stroke of the piston, and the likelihood of a counter rotation of the piston 21 (which is undesirable) is therefore obviated.

The plunger 7 includes an outer core sec- Vtubular extension '5.

tion 33 which has a threaded stem 40 screw ing into the bore 39. y rlhe section 33 has a non-circular. bore 34, in this case oval, receiving the correspondingly shaped rodf35 to the bifurcated head 41 vof which the cylinder lever 8 is pivoted at 19. y

Tac improvement comprises a ratchet 28 which is lirmly secured upon thatend of the plunger sleeve 32 protruding'frorn the In order that the mounting of the ratchetvupon the plunger may bev very secure'use is made of a pluraly ity of pins 29, these being evenly distributed.

Although the use of pinsy is speciied,"the

ratchet 28 may obviously be' secured tothe plunger by other desired means. Thefperiphery of the ratchet is formed into a plus rality of teeth generally indicated 30, the spaces between the teeth being indicated 31 (Figure 10). These teeth are specially shaped, and as particularly shown in Figure 10 have inclined surfaces 45 merging with axially parallel surfaces 46. The surfaces 45 and 46 occur on one side of each tooth, the opposite side being arbitrarilyv rounded as at 47. rlhesurfaces 47 play no part in turning the ratchet although they must be shaped in such manner that the pawl may be passed over without hinderanee of any sort.

The pawl is pivotally mounted upon a bracket 49, which in the present instance is Y.

madeas a separate element so that it may be applied to existing types of air brake cylinders. V

A. stub shaft 50 on the pawl provides the pivotal mounting 'thereof upon the bracketk vThe stub shaft is made nony.

(Fig. y circular as at 501 to receive and hold the weight arm 502 without turning .in respect to the stub shaft. A nut'53 screwed upon the threaded extremity of the stub shaft holds the weight arm in place, and a cotter pin 54V keeps the nut from coming olf. The pawl 4S gravitates to the inclined position shown in full lines in Figure 10 When the ratchet 23 is moved beyond the extremity of the pawl upon an application strokeV of the piston, whereupon the yweight arm 502 rests upon a pin 55 which acts as a. stop, limiting the downward movement of the pawl.

The heel 56 is preferably squared, but regardless of the shape of the end of the heel the upper and lower edges of the pawl are the surface 46 of a tooth upon the upper nie edge of the pawl will have the result of bringing the pawl up to the horizontal,l

position as dotted in Figure 10. The er;- tremitv of the pawl opposite to the pivot 50 is shaped into a point 57 by double beveliiig or rounding the upper and lower edges. The lower front edge is shaped at 58 by a sort of vcombination beveling and rounding to insure avoidance of any friction or bind a. turn ofthe ratchet 28. p in the clockwise direction (arrow a, Fig 9),

,Leonesa ing `between the pawl and the ratchet tooth l next lowest uponthe return or release stroke of the piston.` l y y Theoperation is readily understood. The reader is first askedto assume that'each` of the brake slices 13 and 14, (Fig. 1) is new;

The brake shoesare applied to the wheels` 'wear, so thzliteach succeeding application` stroke of the piston 21 will be represented by an increasing length of stroke of the piston within the cylinder'. All ofj these strokes are for purposes of illustrationzsupposed tobe within range of the Lpafwl {18,'in` other words, as yet the ratchet 38 has not passed beyond the point ofthe pawl. Ultimately the wear 011 the brake shoes will be beyond the point ofthe pawl.

' to suchvex'tent that, the ratchet v28 fwill pass When this takes placethe pawl 48 will drop tothe inclined positionv shown in Figure 10, thisheing due'to the actionof the weight arm` 502 on the other side of the bracket 49. The point 57 will then come Within rangeof theV point of a tooth 30 next lowest. Completion ofthe application stroke will be followed .by the release of pressure against the piston 21 so that the spring43 is permittedto returnthe` piston 21 to the right side of the cylinder 1. Inasmuch as the ratchet 28 is aixedto the plunger ,7" it follows that the tooth; 30 in question must p ride over the nowinclined pawl. As the `reader cani see in Fig." l() it will be the inclined surface 45 that rides upon the upperedge of the pawl, the ultimate result being that the axially parallel' surface 46 will take u a position on top ofthe pawl at a place a out' equally dividedj on each side of the pivot point l50, thereby causing the pawl to rise into the dotted line position in which position it remains until the next slack adjusting operation. 'y

Thefresult ,of the foregoing riding up of" the tooth 30 on the inclined paw-l is tocause This turn will be looking at theratchet from thefront. `This clockwise turn is transmitted to the inner core section 36, theefect being to unscrew the section 36 `from the section 33. After i a numberof `slack adjusting operations the outer section 33 Will be `bound to havebeen unscrewed to a considerable extent asgpic-K.

tui-ed in Figure 6. The pivot" point 19is thus I'nadefto reach out, so to speak, the effect beingto compensate `for the Wear on` the brake shoes. Itinust be borne in inind y'screwed thereon. A pin 61 is inserted thatthe @(135 and Section 33am held from turning, the first by virtue of its connection at" `19`,"the`` second by virtue of theengag'l-` t ment 4of the non-circular bore 34 with` non-circular rod. y inner core section 36 therefore produces the extension of the core section 33with`the result previously stated.

It isnoted principally that the action off the core sections of the plunger? forjthe' purpose `of making adjustments to take" up slack in the braking connections occurs on The unscrewng of theY v the return or release stroke of the piston 21.

In other words, by the action of the" spring `4.3.' The "ratchet 28 and the cci-operating pawl'p`48are located on the outside of the brakecylinder, thus assuming places easily accessible for the purposes of inspection, re`

pair, etc. In practice, it maybe deemed advisable to providesuitable coverings for `the parts' mentioned so that dirt, Water, etc. may

be excluded, butthe use of a protecting cas# ing is optional. 4By virtueof the fact that the ratchetA and its connections are located onthe outside' of thecylinder,it `follows that `the piston 21 is left entirely unobstructed.

There is therefore nothing to prevent a full stroke of thenpiston (see Fig. 5) when the occasion demands. `A full stroke may be required the case of breakage ofsome of the connections, or of the breaklng or falling-olf of one or both of the brake shoes.

The modification in` Figure 11 illustrates an adaptation of the invention` for use upon locomotives. In order to avoid a needless repetition of description all `parts correy sponding with the. foregoing form have similar identifying reference characters. It is `to be noted that the brakecylinder 1 now assumes a vertical position so thatconnection rnay be made with `the locomotive brake system. For this purpose the `exposed ex? tremity of theouter core section 33 is threaded at 59 in order that a collar 60 may be between the ears 62 of t-he collar, the in ex tending through thebifurcated hea 41 of the non-circular rod 35 previously described. The pawl `i8 is pivotally carried by the bracket 49 as before, but the weight arm 502 is' novas7 extended out at right angles so that the pawl may be made to properly assume the inclined .position when the ratchet 2 8 inoves outbeyond range of the pawl. The weight arm then engages the rest pin 55 suitably carried bythe bracket.

`)Vhfile the constructionand arran ementV of the improved slack adjuster is t at of a generally preferred forni, obviously modifications and changes may be made without departing from the spirit of 4the-invfnition or the claims.

the scopeof I clairnz-f` 1l Anfair brake system comprisin brake shoes, articulated connections `inclu inge CAB common pivot, arplunger joined at said common pivot, a piston to which the plunger is connected being movable in either of two 0pposite directions/to perform application and release strokes; in combination an adjustable non-rotatable section slida-ble in respect to. the plunger and having at its inner end a threaded stem occupying said bore, said outer section being connected-with said pivot,

and means associated with the plunger for vturning the plunger upon said release strokes of the piston thereby to unscrew the outerv core section and advance the common pivot for the purposedescribed. f

2, airbrake system 'comprising brake shoes,` articulated :connections including a common pivot, a brake cylinder, a piston'operable therein havinga tubular plunger connected therewith for rcciprocation and rotationand joined with said connections at the common pivot, said piston being movable in one direction by lluid'pressure to producean application or' the brake shoes, a spring inthe cylinder reacting against the piston moving it in the opposite direction to cause a release ot the brake shoes; in combination, a sectional core forming part of the plunger comprising a rotatable inner section secured to the plunger tor movement therewith and a non-rotatable outer section having threaded engagement with the inner secf tion by which the plunger is joined with said connections, apawl, a bracket mounted upon part oi the cylinder pivotally carrying the pawl, a ratchet carried by said inner section engaging the pawl at successive ratchet teeth after certain application strokes oi' the piston to cause turning ot the inner core section byk reaction of the spring against the piston on lthe release stroke.

An air brake system comprising a brakecylinder, a piston operable in the cylindema plunger carried by and havingrotary and rectilinear motion with the piston including a sleeve protruding from the cylinder and having a two-sectional core, one section being secured to and moving with the plunger' sleeve and piston, the other extending therefrom for connection to the brake connections ot the piston and having rectilinear motion only, afpawl carried by the brake cylinder, a ratchet carried by the protruding end o'lf'said plunger sleeve, means moving the piston in one direction to perform a brake-release stroke, said pawl catching a new tooth of the ratchet on certain release strokes of the piston thereby turning the sleeve connected core section and threaded means connecting the core sections causing rectilinear advancement of one core section in respect to the plunger for the purpose described.

4. Means for ad'usting the slack in` the rigging of air brake systems comprising a pressure cylinder, a piston therein, a tubular plunger connected thereto for reciprocation and rotation with said piston and lwith its outer end projecting beyond the cylinder, a

sectional core 'foi/'inin, l part of said plunger including un iniieiksection secuiedito and rotatable with the plunger'and piston and a iion-rotatable outer core section providing va rigging actuator and havingthreaded en gagen'ient with the inner corevsection and forming an extension ot tliieplunger for connection to the brake rigging, means coopera-ting with the said'projecting outer end oi" the tubular plunger andy conditioned by Y brake applying movement of the plunger beyoud a predetermined amount to impart ro'- tatory nfiovement to theplunger and piston upon the return or brake-releasing movement tliereo'l-tliereby through said threaded core sections causing longitudinal adjustment off the rigging actuatorcore in compensation ior slack. j

5. Means tor adjusting the slack Vin. the rigging'oiLl air brake systemscoinprising a pressure cylinder, a piston therein, a tubular plunger connected thereto' for reciproca-Y tion and rotation with said pistonand with its outer end projecting beyond the cylinder, a sectional core forming part of said plunger including an inner section secured to and rotatable withthe plunger and piston and a non-rotatable outer core section providing a' rigging actuator and having threaded engagement with the inner core section and! forming an extension of the plunger for con# nection to the brake rigging, co-acting rotas tor members l'or the plunger and piston, one

of which is mounted on the outer projecting lun rotative movement to the plunger thereby i through said threaded connections, Iextending the rigging actuator compensation for slack.

6. Means for adjustingithe slack in the rigging of air brake systems'comprising a pressure cylinder, a piston therein, a tubular plunger connected therewith for reciprocation land rotation and having its free end extended beyond tliecylinder, ai non-rotatable rigging actuator forming an extensionof said plunger and having threaded engagelongitudinally in lying pawl and ratchet surfaces whereupon said pawl will move and upon the return 10 stroke of the piston rod be positioned to engage and impart rotative movement to the `ratchet and plunger, 'therebf extending the rigging actuator longitudina tion for slack.

WILLIAM S. DE CAMP.

y in compensa- 

